Diesters of 1-ketophosphonic acids



Patented Dec. 20, 1949 2,491,820 DIES'I'ERS OF 'l-KETOPHOSPHONIC ACIDS Maurice Leon Ernsberger,

- signor to E. I. du Pont pany, Wilmington, Del ware Wilmington, DeL, asde Nemours & Coma corporation of Dela- No Drawing. Application May 16, 1946,

Serial No. 670,295

17 Claims. (Cl. 260-461) This invention relates to new organic compounds of phosphorus. More particularly, it relates to new esters of l-ketophosphonic acids.

An object of this invention is to make available a new class of organic compounds, the diesters of l-ketophosphonic acids. Another object is to provide a process for preparing these new esters. Another object is to prepare polymeric derivatives oi polymerizable l-ketophosphonic acid esters. Other objects will appear hereinafter.

These objects are accomplished by the invention of diesters of l-ketophosponic acids and the polymers of certain of them and of a process for preparing such products which comprises reacting a carboxylic acid chloride or bromide with a neutral phosphite ester and isolating the product.

The new products of this invention have the eneral formula RCOPO (OR') 3 by the following weight.

The invention is illustrated examples wherein parts are by EXAMPLEI uemyz I-ketoethanephosphondte, cmc'omo) (OC'aHs):

One hundred fifty-six parts of acetyl chloride ras placed in a reaction vessel equipped with tirring means, addition means, and a condenser, be open end of which was attached to a trap ooled in a mixture of Dry Ice and acetone. *ifty-flve parts of triethyl phosphite was added ropwise while maintaining the temperature elow reflux. When the addition was complete 1e reaction mixture was refluxed for one-half our. At this time the "Dry Ice cold trap was mud to contains parts of ethyl chloride boiling t 8-13 C. The reaction mixture was fraconated and after removing the excess acetyl iloride, 40.5 parts, or 67 per cent of the theoretical amount of diethyl l-ketoethanephosphonate was collected, B. P. 114-115 C., at 20 mm. or 83 C. at 4 mm. Refractive index 1.4200 at 26 C.

Analysis-Calculated for CsH1a04P: 0.40.00; H, 7.25; P, 17.2. Found: C, 40.42; H, 7.46; P, 16.51, 16.55.

Diethyl l-ketoethanephosphonate is soluble in water, or in dilute alkali with the evolution of heat. It does not react with 2,4-dinitrophenylhydrazine test reagent. It is decomposed on boiling with water with the formation of acetic acid. An aqueous solution of 9.0 g. of this ester in 10 cc. of water was refluxed for one-half hour. This reaction mixture was distilled and the condensed volatile liquid was neutralized with sodium hydroxide and evaporated to dryness. The dry salt was used in preparing a p-bromophenacyl ester which melted at 82-83.5 C. Corr.) after repeated recrystallization from alcohol. The p-bromophenacyl ester of acetic acid is reported to melt at 85 C.

EXAMPLE H methyl 1 Iceto-Z-methyl-Z-propenephosphmtate: polymers [CH2=C'(CH3) COPO(OC2H5) 21:

Forty parts of methacrylyl chloride, B. P.

97.5-98.5 C. stabilized with hydroquinone, was

'placed in a reaction vessel equipped with a thermometer, stirring means, addition means, and a condenser. Fifty-live parts of triethyl phosphite was added dropwise while holding the temperature of the reaction mixture at 40-55 C. by means of external cooling. A steady stream of gas was evolved during the addition which was completed in about thirty minutes. The reaction mixture was then heated to 90 C. for twenty minutes. About ten moved by heating under a vacuum of 5 mm. at a temperature of 200 C. The 56 parts of residue represented a yield of 59 per cent of the theory of a polymer of diethyl 1-keto-2-methyl 2-propenephosphonate.

Analysis-Calculated for (CaH15O4P): C, 46.6; H, 7.28; P, 15.05; molecular weight (206) Found: C, 45.68; H. 7.45; P. 15.02; molecular weight (ebullioscopic in benzene) 480; 450.

The polymer was a viscous, water-soluble liquid which acquired a grease-like consistency on storage. It decolorized bromine in carbon tetrachloride solution and could be salted out of an aqueparts of low boiling material was re-..

ous solution by adding sodium bisulfite. Addition of benzoylperoxide followed by heating resulted in the formation of a very viscous oil which had a molecular weight (ebullioscopic in alcohol) of 532; 510.

The invention has been described with particular reference to diethyl i-ketoethanephosphonate and diethyl l-keto-2 methyl 2 propenephosphonate since these compounds are typical representatives of the class of esters of l-ketophosphonic acids. However, the invention is generally applicable to the preparationof diesters of l-ketophosphonic acids and particularly those of the formula wherein R and R are monovalent hydrocarbon phite, tricyclohexyl phosphite, tribenzyl phosphite, triohenyl phosphite, as well as mixed phosphites. The trialkyl phosphites, particularly the lower alkyl esters having up to six carbon atoms in the alkvl group. are preferred.

While the invention has been illustrated with acetyl and methacrylyl chlorides, monocarboxylic acid chlorides and bromides in general may 4 I lated by distillation if a liquid, by crystallization if a solid, or as the polymer in the case of esters of unsaturated keto'phosphonic acids. In the last case the product may be purified by fractional "precipitation or by chemical and physical treatment to remove contaminating materials.

The unsaturated l-ketophosphonic acid esters may be isolated and purified through distillation in their monomeric form and then polymerized or copolymerized with suitable catalysts such as benzoyl peroxide, persulfate-bisulflte, boron fluoride, or aluminum chloride catalysts. They may also be polymerized in part during their isolation and subsequently polymerized to a higher polymer as illustrated in the examples or they may be polymerized without isolation at all. Heat, oxygen, and ultraviolet light may also be used to catalyze the polymerization and bulk, emulsion, granular, or solution techniques may be used.

The products of this invention are of interest as plasticizers for polymers and copolymers', as

7 modifying agents for internal combustion en ne fuels, for instance as metal deactivators, as addition agents for lubricating oils and as stabilizers for polymers, oils, and hydrocarbons.

The foregoing detailed description has been given for clearness of understanding only and no be employed, including propionyl chloride, benzoyl chloride, phenylacetyl bromide, trimethylacetyl chloride, isobutyryl bromide, acetyl bromide, trichloroacetyl chloride, cinnamoyl chloride, oleic acid chloride, propargylic acid chloride, crotonyl bromide, sorbic acid chloride, beta-furylacrylic acid chloride, etc. The acyl chlorides unnecessary limitations are to be understood therefrom. The invention is not limited to the exact details shown and described for obvious modifications willoccur to those skilled in the art. 7

What is claimed is:

1. Diethyl l-ketoethanephosphonate.

2. A diester of a l-ketophosphonic acid said ester having the formula R-C0PO(OR'): wherein R. and R' are alkyl radicals of not more than six carbon atoms.

and bromides of the saturated and unsaturated fatty acids having up to six carbon atoms are preferred because they are cheaper, more readily available, and lend themselves particularly well to reaction.

For the preparation of polymerizable esters the acid chloride or bromide is preferably an a pha methylene acid chloride or bromide, i. e. one having a methylene group attached byv an oleflnic double bond to the carbon alpha to the 0001 or COBr group. v

The reaction between the triester of phosphorous acid and the acyl halide may be carried out at any temperature, up tothe decomposition point I of the reactants, which permits a suitable rate of reaction. In general, this temperature is above 20 6., preferably between 25 and 200 C.

It is convenient to remove the by-product hydrocarbon halide as it forms to prevent sidereaction of this halide with the phosphite. The reaction may, however, be carried out in a closed vessel under pressure, bleeding oil the hydrocarbon halide if desired.- In general, no solvent is necessary, but a solvent or diluent may be used to aid in lowering the reaction rate when violent reaction occurs. or in promoting the reaction when sluggish as with high molecular weight reactants. It is best to use substantially equivalent amounts of reactants though an excess of one or the other will do no harm. In particular an excess of the acyl halide may be desirable to prevent side reaction with the by-product hydrocarbon halide. The product is conveniently iso- 3. Diethyl l-keto-2-methyl-2-propenephosphonate.

4. A polymer of diethyl 1-keto-2-methyl-2 propenephosphonate.

5. A diester of a i-ketophosphonic acid said ester having the formula R-CO--PO(OR'): wherein R is an alkyl radical of not more than six carbon atoms and R is an acyclic hydrocarbon radical of not more than six carbons and contains a methylene group attached by an oleflnlc double bond to the carbon alpha to the CO group.

6. A polymer of a diester of a i-ketophosphonic acid said ester having the formula wherein R is an alkyl radical of not more than six carbon atoms and R is an acyclic hydrocarbon radical of not more than six carbons and contains a methylene group attached by an o efinic double bond to the carbon alpha to the C0 group. i

'7. A diester of a l-ketophosphonic acid said ester having the formula RCO--PO(OR'): wherein R and R are acyclic hydrocarbon radicals. Y

8. Adiester of a l-ketophosphonic acid said ester having the' formula R,COPO(OR'): wherein R and R are acyclic hydrocarbon radicals of not more than six carbon atoms.

9. A diester of a l-ketophosphonic acid said ester having the formula R--COPO(OR'): wherein R and R are alkyl radicals.

10. Process of preparing diesters of l-ketophosphonic acid which comprises reacting an orthoester of phosphorous acid with a member of the class consisting of monocarboxylic acid chloride! and bromides.

acea,

11. Process of dicsters of l-ketophosphonic acid which comprises reacting an orthoester of phosphorous acid with a monocarboxylic acid chloride.

12. Process of preparing diesters of l-ketophosphonic acids which comprises reacting a trialwl phosphite with a saturated fatty acid chloride.

13. Process of preparing diethyl l-ketophosphonate which compriss reacting triethyl phosphite with ace yl chloride.

14. A diester of a monovalent acyclic 7 15. A liquid polymer of diethyl l-keto-Z- methyi-z-propenephosphonate. V

16. A liquid polymer of a diester of a i-ketophosphonic acid said ester having the formula R-CO PO(OR')2 wherein R is an alkyl radical ofnotmorethansixcarbonatomsand Risen acyclic hydrocarbon radical of not more than six carbons and contains a methylene group attached by an olefinic double bond to thecarbon alpha to the CO group.

17. A liquid diestezof a l-ketophosphonic acid which acid is acyclic bon except for the 4688 and 4689 (abstract of a group and the (mo oxygen and whereinthe two acid hydrogens 'of the by monoyalent acid are replaced acyclic hydrocarbon radicals.

MAURICE LEON ERNSBERGER.

The following 1mm STATES PATENTS Number 2,389,576 2,397,422

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Kosolalloif KcsolaDOlf Mar. 26, 19411 OTHER REFERENCES Kabachnik et 2.1.,

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